ArticlesAugust 2011DTS-10 vs. DTS LMS-R

Introduction

The DTS-10 is a passive DIY subwoofer kit designed by Tom Danley of Danley Sound Labs that was made available as a flat pack for a limited time at a very attractive price. It is regarded as one of the most capable home theater subwoofers available today.

Configuration

The kit is a tapped horn alignment which has been popularized by Danley in the last few years and is utilized heavily in their product line. This enclosure alignment is quite inventive and attempts to make use of both sides of the radiators coupled into an expanding horn path in different locations that improve the efficiency and leveraging of the radiators over a certain bandwidth.

The DTS-10 itself utilizes dual 12" long throw woofers, nominally 4 ohms each, built by Eminence and featuring 3" coils, cast frames and dual stacked magnets with an impressive amount of motor force for a long throw 12. The DTS-10 is tuned especially low with the cabinet loading the drivers all of the way down to 14hz or so and features a relatively high sensitivity especially for a subwoofer with such an extended response.

System Differences

For this review, we compared the DTS-10 as delivered with the stock drivers against the same cabinet loaded with a pair of TC Sounds LMS-R 12" woofers, namely the DTS LMS-R. These are the latest generation of LMS drivers which provide very long linear excursion, an aluminum shorting ring in the motor, and relatively good BL product for their size. The LMSR's are less efficient than the Eminence drivers, in part because they have a higher moving mass, but they provide a good deal greater linear displacement and also fit the bolt pattern in the cabinet.

The LMSR-12 drivers just barely fit through the hatch panel into the cabinet and a mounting ring of an extra layer of 18mm birch ply had to be fashioned to provide clearance for the corner driver due to the deeper and larger motor. There was also some modification needed under the down-firing driver to provide extra clearance for the considerable excursion abilities of the LMS-R drivers.

The DTS-10 cabinet was simulated with the stock and LMS-R woofers beforehand to get an idea of how the system response might change. In general, it appeared that the switch would trade off some efficiency and a slightly rougher response shape for extra power handling and low end output before driver over-excursion. The line of thinking is that in home theater use, the 10-30hz area is aggressively used and driver excursion is often the first limitation to come into play rather than amplifier or thermal limitations in the upper bass range.

Test Results

The 1 watt voltage test indicates the overall response differences and sensitivity of each system. The drivers were wired in series for these tests giving a nominal 8 ohm load for each. Bear in mind that the voltage used is one that corresponds to roughly 1 watt of power into the measured impedance minimum within the subwoofers useable pass-band, and not a typical fixed voltage measurement, regardless of the actual impedance of each. This method ensures that neither setup ever receives more than 1 watt at any frequency during the measurement.

From here we can see the stock drivers pull 2-3dB better SPL on average with our 100w 10 meter measurement, indicating the small signal sensitivity difference we measured directly from the drivers. The LMS-R 12 is around 83.9dB while the other is above 87.3, or about a 3.4dB difference. The stock system has a definite sensitivity advantage.

Also note the changes to the frequency response. A tapped horn system is much more particular about driver characteristics than a simple sealed or bass reflex system. Minor changes in the amount of motor force, moving mass, inductance, suspension compliance and radiating area can have a profound impact on the system characteristics. In this case, the extra size of the motor on the LMS-R drivers in the horn's path, and the need for the extra mounting ring may even be contributing. The stock configuration has a smoother basic response shape.

Applying high power to the system, the advantage of the linear travel that the LMS-Rs offer start to outweigh the sensitivity differences as we get a 2-3dB advantage in SPL in favor of the TC drivers before distress noises start to make themselves known. You can see that with this much higher power input into the system, the frequency response seems to flatten out due to thermal or perhaps also air flow compression in the horn path.

Conclusion

Overall, the stock DTS-10 has a little better native response and is lighter, cheaper, and more sensitive. Switching to the LMS-R drivers provides extra low-end grunt in the deep bass, and from looking at the distortion measurements presented elsewhere, a little bit lower total harmonic distortion overall.

Both really need a steep high pass filter at 12 to 14hz to prevent the drivers from unloading below the cabinets cut off. The stock DTS-10 was excursion limited at or near 20hz with enough power and that is really its main bottle neck in output. It has considerable output there already as can be seen in the tests, but that's the area it runs into trouble first. This is a very content rich zone for many action blockbuster movies. The TC drivers, with their much greater excursion abilities, allow for an extra 3 or 4db of peak output in the lowest frequencies as can be seen in the burst output tests. Some may feel like the tradeoffs involved in switching to the LMS-R drivers are not worthwhile; others may think that for the extra low bass headroom offered and the lower distortion overall that it is. After all, this is a big, high output, extended low frequency device.

The LMS-R's will add nearly $740 more to the system cost and an extra 30lbs in weight. Unfortunately, the kit is not available any longer after completing the second period of its offering from Danley Sound Labs, which was partly due to its unexpectedly high popular demand. However, the DTS-10 is still available as a completed subwoofer from Danley Sound and is an exceptionally potent subwoofer in stock form.